Sziklai pair

Sziklai a pair, also referred to as a complementary Darlington circuit, an electronic circuit comprising two bipolar transistors is similar to a Darlington circuit in which, in contrast to these two different bipolar transistors, the NPN transistor and a PNP transistor find use. The circuit is named after the American -Hungarian engineer George Clifford Sziklai, which she developed in 1953.

Functions and properties

In the literature, two variants of a Sziklai pair are described. Depending on the arrangement of the NPN and PNP transistor pair acts as the Sziklai NPN or PNP transistor. By the combination of the two complementary transistors, a higher current gain than with individual bipolar transistors is achieved.

The base -emitter voltage UBE, the voltage between the terminals marked B and E in the adjacent circuit diagram, is in both versions around 0.6 V; In contrast to the Darlington circuit with the twice the base-emitter voltage of 1.2 V. As for the Darlington stages is in the saturation voltage of the collector- emitter path of UCE about 0.6 V. In practical applications, is also a resistance in the range of 0.1-1 kOhm switched between emitter and base of Q2 to reduce the turn-off times for fast switching applications.

Application

The Sziklai pair played despite technical advantages, first against the Darlington stage in practical circuit design a subordinate role, since two npn transistors of the Darlington circuit can be manufactured easily on a common semiconductor substrate as a combination of NPN and PNP transistor. Application of Complementary Darlington circuit are in the range of bipolar, integrated amplifiers and their push-pull output.